Dairy cow's milk production is determined to a large extent by the healthiness of the udders. Therefore, dairy farmers must pay the necessary attention to keeping "the production facilities" healthy to prevent subclinical or clinical mastitis. It is generally accepted that subclinical mastitis occurs when the somatic cell count is over 200.000, even without symptoms [1].
The damage caused by mastitis is not small. The average cost of clinical mastitis varies between studies. In the USA the average cost of a case of clinical mastitis in the first 30 days in lactation is a whopping 444 euros [2]. In The Netherlands, the economic losses of a clinical case were calculated as 210 euros [3]. A Swedish study looked at both clinical and subclinical mastitis. The cost of clinical mastitis was 275 euros per case, while the cost of subclinical mastitis averaged on 60 euros per case [4]. Although the cost of a case of subclinical mastitis is lower, we should not forget that subclinical mastitis